1. Technical Field of the Invention
The present invention relates to electric rotary machines having armature coils made of flat type wires and, more particularly to an electric rotary machine, an armature for the electric rotary machine, a method of manufacturing the electric rotary machine and a forming machine for the armature of the electric rotary machine.
2. Description of the Related Art
In recent years, an electric rotary machine (especially a starter) for installation on a vehicle requires an effort to minimize a structure with lightweight aimed at decreasing an installation space and improving fuel consumption. To achieve such an aim, an attempt is made to provide a model an armature coil adopting a flat type wire to provide an improved lamination rate with an increase in output torque for thereby achieving the miniaturization of an armature with lightweight.
However, it is well known that the flat type wire has a narrower creeping distance between upper and lower coils at an intersecting region where the upper and lower coils intersect with each other than that of a round wire with a difficulty encountered in ensuring a safety insulating distance. Additionally, the flat type wire is hard to have a coil set (especially in the long side direction of the wire), causing an issue to arise in ensuring an insulating distance between the upper and lower coils at the intersecting region where the upper and lower coils intersect with each other.
To address such an issue, U.S. Pat. No. 5,619,088 proposes an armature for an electric rotary machine. As shown in FIG. 7, the armature has a lower coil extension 100 and an upper coil extension 200 that intersect with each other. The lower coil extension 100 and the upper coil extension 200 are formed with cutout (stepped) portions 110, 210, respectively, at an intersection region where the lower and upper coil extensions 100, 200 intersect with each other, thereby ensuring an insulating gap between these coil extensions 100, 200.
With such a related art structure, press punching intermediate areas of the lower coil extension 100 and the upper coil extension 200 at the intersection region allows the cutout portions 110, 210 to be formed. With the cutout portions 110, 210 formed by press punching, burrs are formed at edges of the cutout portions 110, 210. These burrs are feared of causing damage to insulation layers of the coils with the resultant occurrence of short-circuiting. When an attempt is made to deburr, the number of man-hour increases with the resultant increase in manufacturing cost.
Further, press punching the lower coil extension 100 and the upper coil extension 200 to form the cutout (stepped) portions 110, 210 causes the insulation films to be peeled off from the lower coil extension 100 and the upper coil extension 200, respectively. This results in an increase of short-circuiting.
The number of coils to be subjected to press punching ranges from approximately 100 to 200 pieces. Thus, many number of press punching operations needs to be carried out with an increased load born by a press die, with a fear of shortening of die life.
Further, the burrs caused during press punching remain on the coils with adverse affects caused in subsequent steps.
Furthermore, the burrs, occurring during press punching, fly apart in equipment, resulting in an increase in labor hour for cleaning equipment.
With a view to addressing the occurrence of short-circuiting, large number of interlayer insulating sheets needs to be disposed between the lower coil extensions 100 and the upper coil extensions 200. This causes an increase in the number of component parts and production equipment becomes complicated in structure.